A frequent problem in dentistry is the devitalization of a tooth, that is the removal of the dental pulp from the pulp chamber or cavity. This is generally carried out by means of flexible thin reamers. These reamers comprise a handle and a flexible blade with helicoidal cutting edge and are used by rotating them manually or by motor; their flexibility allows them fit to pulp chambers of different curving. Generally a series of reamers or files of increasing diameter are used to empty the pulp chamber. A risk present in this way of proceeding is that the operator does not have an exact perception of the point in the cavity reached by the tip of the reamer; thus it can happen that the emptying of the pulp chamber is incomplete or the tooth apex is pierced, and in both cases a clinically valid methodology for a good devitalization is not followed.